import java.util.StringJoiner;

public class zifu {
    public static void main(String[] args) {
        StringJoiner sj = new StringJoiner(",","[","]");
        int len = sj.add("aaa").add("bbb").add("ccc").length();
        //len不仅是字符串的长度，还包括了[]和,的长度
        System.out.println(len);
    }
}
